An image forming apparatus known in the prior art includes a conveying path, through which paper is conveyed to an image forming unit, and a re-conveying path, which joins the conveying path on the upstream side of the image forming apparatus in a conveying direction. This type of image forming apparatus has an actuator that detects paper, the actuator being disposed near the downstream side of the junction between the conveying path and the re-conveying path in the conveying direction. If the conveying path is wide at a position at which the actuator is disposed, the top of paper is likely to pass various positions, so the top is likely to come into contact with the actuator at various positions. This causes the actuator to tend to operate at various times.
In view of this, if ribs protruding upward are provided at both sides of the actuator to narrow the conveying path at the position of the actuator by an amount by which the ribs protrude, the conveyed paper is less likely to come into contact the actuator at various positions. This enables the actuator to detect the paper more accurately.
If, however, the above rib is provided in an image forming apparatus so that the rib extends to the re-conveying path, it is narrowed at a position immediately before the junction between the conveying path and the re-conveying path. This may cause an increase in a resistance that prevents paper from being easily conveyed through the conveying path on the upstream side of the rib in the conveying direction.